/How does the percentage of active ingredient in a product relate to the amount of protection it gives?

Typically, the more active ingredient a product contains the longer it provides protection from mosquito bites. The concentration of different active ingredients cannot be directly compared (that is, 10 percent concentration of one product doesn’t mean it works exactly the same as 10 percent concentration of another product.)

DEET is an effective active ingredient found in many repellent products and in a variety of formulations. A study conducted in 2002 found:

  • A product containing 23.8 percent DEET provided an average of 5 hours of protection from mosquito bites
  • A product containing 20 percent DEET provided almost 4 hours of protection
  • A product with 6.65 percent DEET provided almost 2 hours of protection
  • Products with 4.75 percent DEET were both able to provide roughly 1 and a half hour of protection

These examples represent results from only one study and are only included to provide a general idea of how such products may work. Actual protection will vary widely based on conditions such as temperature, perspiration, and water exposure.

Choose a repellent that provides protection for the amount of time that you will be outdoors. A product with a higher percent of active ingredient is a good choice if you will be outdoors for several hours while a product with a lower concentration can be used if time outdoors will be limited. Simply re-apply repellent (following label instructions) if you are outdoors for a longer time than expected and start to be bitten by mosquitoes.